A C T I V I T I E S |
AUTÓKUT and its predecessor JÁFI were established as a Hungarian R&D
institute for development and testing of on-road and off-road vehicles
and their main components. Activity field was the tests of the vehicles
designed and developed in the Institute, and frequently - almost from
the establishment exclusively - serving for military purposes. Their
successor JÁFI-AUTÓKUT Engineering
The objective of the test is to
supply
detailed data for comprehensive assessment of the vehicle's usability
and by this the marketing conditions, such as:
The purpose of this test is to
discover
the damages occurring during operation and occasional weak points
foretelling the service-life of the vehicle and the subassemblies, as
well as to determine the serviceability and to elaborate proposals on
elimination of the discovered troubles.
We perform the specified purpose
test
of some vehicle subassembly in order to assure the data necessary for
the development. These tests serve also for detailed discovery of the
problems occurring at the manufacture, application and operation. Under
the special tests the ergonomic, as well as both the active and the
passive safety tests can also be listed. Belonging to our tasks -
frequently preceding the above listed measurements and tests - were the
installation of certain new main units and subassemblies to the
vehicle,
the assembly and the trial run of the special vehicles designed and
produced by AUTÓKUT. As can be seen from the above, our tests
cover
both
the entirety and the subassemblies of the vehicle. For performing the
test we possess up-to-date instrumentation, comprehensive professional
knowledge and experiences and as the authorized test station of the
Department of Transportation we are also commissioned to perform
approval tests according to certain ECE regulations, the results of
which are accepted world-wide in the affiliated countries.
For the Department of
Transportation
our expert opinion summarizing the tests and results serves as base for
issuing registration and type certification of a certain vehicle type.
In the past years we prepared complete or partial type test expert
reports both for the manufacturing and operating companies (Ikarus
és
Ikarusbus Corp., Ikarus Special Coach Factory Ltd., RÁBA Corp.,
Csepel
Automobile Factory Ltd., VOLÁN Corp., etc.), as well as more and
more
frequently for small-scale enterprises. Within the regional economic
organization - the so-called Economic Commission for Europe, ECE - of
the UN, the Vehicle Development Institute (JÁFI), then
AUTÓKUT since
1959 deals with domestic coordination of the standardization agreement
as per Geneva Conventions adopted in 1958 on the technical
specification
and the mutual acceptance of the approvals issued accordingly.
The workgroup WP.29 - acting in this special field - during 40 years elaborated 110 technical specifications, all of which were supplemented to the Geneva Conventions of 1958. The Hungarian party joined the Conventions according to the Decree-Law No. 21 of 1960 as the 7th state. After amendment of the original Conventions in 1995, in Hungary the amended version came into force by the Law LIII. of 1997. The Hungarian party accepted 107 regulations to date, and 50 specified approval tests from these shall be performed by AUTÓKUT on commission from the Transportation and the Industrial portfolio. This means that the approval issued by the Hungarian authority on basis of the test certificate or expert opinion on the tests performed by AUTÓKUT shall be accepted by the other 29 affiliated countries of the Conventions. Thus this certification test activity of AUTÓKUT is in possession of an international license registered by the UN Secretariat. In the test activity AUTÓKUT endeavors to perform the tasks by means of the most modern methods, as well as more and more precise instruments. For this purpose in our work we follow and apply both the national and sectoral standards and the international (ECE, EEC) regulations and directives.
The laboratories perform the
parameter
determination, function and service-life tests of the experimental
models, on occasion together with the necessary assembly works. The
test
reports contain the analytical assessment and the modification
proposals, as well. The material condition for the laboratory tests of
the complete vehicle was assured by installation of the hydraulic
operating road simulator, the so-called Hydropuls equipment in 1975.
During the tests we deal with two basic task-groups. The first is the
complex vibration analysis
of the vehicles. The
cause of the vehicle
structure malfunctions and damages is mostly the strain generating from
the vibrations.Likewise the vibration features significantly effect the
passenger comfort and the road holding properties of the vehicle.
The designer can follow certain vibration theory features, such as the suspension vibrations, with rather good approximation, by calculation. Others, like the engine mount, may be calculated only with coarser approximation. Finally such phenomena, like the roof vibrations, the flexible continuum vibrations of the window and door column or the body, during the practical design work may be followed by calculation, if any, only with high effort and low accuracy. For clarification of such hard to handle tasks the vibration tests of the vehicle can be used. The main idea of the vehicle's vibration test is very simple. The vehicle is positioned to test- bench and through its wheels (like in realty) is brought to harmonic vibration. Varying the excitation amplitude, frequency and phase locus, the transfer functions related to different units (axles, body, engine, etc.) of the vehicle are prepared. On basis of these the natural frequencies of the system, as well as the rate of the vibration insulation at certain places are determined, that is how the suspensions filtrate or amplify the excitation effects from the road. The measurement series is performed on each vibration forms of the components.
The vibration test reviews the
features
of the vehicle as a complex vibration system and among others answers
the following important questions: Is the natural frequency of the
given
subassembly within the optimum range? Is the damping rate of the given
subassembly suitable? Are there interacting subsystems in the whole
system due to the identical natural frequencies? Are there vibrations
exciting each other due to their vibration coupling? During the
prototype test in the Hydropuls laboratory, the vibration analysis may
be followed by laboratory endurance test. Basically the endurance test
means the laboratory simulation of a highway run test. Practically it
is
performed by profile measurements on the road network characteristic to
operation of the given type, using the road profile measuring
instrument
and method developed by us. The signal of the measured road profile is
recorded on magnetic tape and by playback the travel on the selected
road section can be simulated. Since our aim is the endurance test of
the vehicle, it is practicable to select a rough road section
representing high stress. By this the test can be accelerated so, that
"traveled distance" on the test-bench shall be considered weighted
relative to an average stress.
During endurance test the vehicle
wheels do not rotate, but the whole structure - except the drive chain
-
is exposed to actual loads and damages. Our road profile measurement
technology provides possibility for considering the incidentally
special
road conditions of the expected ser- vice conditions already during the
prototype test. Further advantages of the Hydropuls test are the
following: - the test performed on the equipment are accurately
repeatable, which generally cannot be assured during the highway
measurements; - even with the most modern measuring devices, visual
monitoring of the individual parts' behavior may frequently be very
useful, which can excellently be performed on the equipment. Here are
two brief examples to prove the above: Within the project Copernicus we
developed the so-called bus expert system in cooperation with experts
of
four countries. We had the task to perform the vibration test of the
bus
on the Hydropuls test-bench, then to setup such a computer model, which
is also suitable for simulating the flexible vibrations of a bus body
and returns the measurement results. In the project Eurosping together
with English, Czech, Danish and other foreign companies we test plastic
leaf springs in built-in state, both on test track and the Hydropuls
equipment. The first phase aimed to develop plastic leaf spring
serviceable even in heavy trucks successfully finished this year, while
the subject of the second phase is development of the so-called road-
friendly suspension, similar to air springs.
Recently our customers instead of
the
Hydropuls test sometimes employed that service and its results by which
the stress analysis can be performed on the vehicle under normal
operating conditions. The cause of this might be that the test is more
"cost-saving" and the results are supplied faster, than at the
Hydropuls
test, though cannot replace it.
We are able to perform laboratory test of the main units and the subassemblies prior to installation into the vehicle or for discovering causes of phenomena occurring during the operation. The purpose of this might be certification, determination of functional characteristics, trouble- shooting or endurance test. The equipment source for testing the main units and subassemblies is very variable. Lately the tests belonging to the so-called passive safety (e.g. safety helmet, bus seat, safety belt tie points, baby seat, etc.) form a very dynamically developing field and volume. A significant part of the equipment is of own design and was produced by Jáfi-AUTÓKUT, of course using COST elements and units.
The instrumentation of the tests
is
assured partly by using special electric measuring gages designed and
prepared by the chief of experiments, partly by purchasing modern
measuring equipment. Connecting these equipment and instruments to
computer we are able to digitize the control, the measurement data
acquisition and the evaluation, as well as to comply with the
reliability and reproducibility requirements, what is essential
nowadays. In the following for review we briefly list our most
characteristic laboratory tests of the recent few years, stating the
customer:
In the following sections from
the test
activities, unlike the other fields, we discuss in details the
development of the bus passive safety, the test results and methods
thereof, due to the outstanding activity as compared to facilities of
the domestic automotive industry and to the European research field,
The passive safety tests of the buses in Hungary were started in the very beginning of the seventies - practically at the same time as car developments on the other more developed part of the World - as a result of the following main effects: introduction of the bus series 200 in the series production, needs to specify the increased technical requirements; Hungary's join in the UN ECE subcommittee's work in 1970 for elaborating the European Automotive Specifications; start of the domestic vehicle development program in 1971 providing possibility for establishing a special test base in AUTÓKUT.
Because of the large dimensions, character and high costs of the buses, as well as due to the unsuitability of the test means and methods developed for the passenger cars, few passive safety tests were performed in Europe, thus in this field Hungary played world-leading role.
For establishing the test
condition in
the first half of the seventies a pendulum impact tester and a tipper
gear was constructed, further we purchased 3 dummies, as well as one
Schenck Hydropuls equipment for vibration test, measuring tape
recorders, acceleration transmitters and computers. From the middle of
the eighties, with strict filtration of the central and other company
supports, only the ordinary resource development remained for us, but
in
spite of this we constructed an electro-hydraulic
impact tester, a
roll-over tester, a helmet
testing equipment and new dummies (presently
we have 3 adult and 4 child dummies, as well as a mannequin measuring
the H point of the seats), further we renewed the MTS tensile-strength
testing machine.
Up to the end of the eighties
there was
no authoritative European regulation on passive safety of the buses,
however AUTÓKUT elaborated already more than 3 dozens of bus
specifications (AK specifications project) half of which dealt with the
passive safety. On basis of the research results the passive safety
topics related to buses can be grouped as follows:
From analyzing the domestic accidents, the first roof strength tests were performed with IK 250 and IK 55 buses in 1972. There were three different test series: static roof loading, static roll-over to roof from side laying position, roll-over test on slope. (The last roof strength test on slope happened in 1983 by IK 255.)
In AUTÓKUT the roof strength test was and even presently is an emphasized topic. From the related researches of the past period the following fields can be accentuated: design and installation of roll over frames to the running bus types, computer analysis of the roll-over kinetics and kinematics, strength test of the passenger seat anchorages laboratory test on frame sections, scale model roll-over tests, elaboration of simulation test procedure.
Between 1972 and 1983 we performed seven complete roll-over tests on slope. Initial opposition of the West-European countries ceased on effect of severe accidents, however as a result of compromise the EGB 66. specifications enacted in 1986 contains merely roll-over from vertical position in 800 mm to concrete surface. According to AUTÓKUT experts, the multiple roll-over test - developed by AUTÓKUT - would mean higher requirement and safety.
We dealt much with strength test of the bus frame structures, despite there are valid European specifications merely for the passenger seats, as well as for the seat and seat belt fastening. From the related test series of the past 25 years the following topics can be emphasized: elaboration of specifications on the bus bumpers, research of stability losses at bottom frames and side members, tests of front wall energy absorption capacity, driver seat safety platform to assure driver's survival space, requirements on driver's compartment for frontal collision, complete bus collision tests for determining the standard accident situation of the frontal collision, passenger car and bus side collision tests.
After accident statistic analysis
of
the domestic fire accidents, in 1983 we performed simulations on two
standstill IK 255 buses by generating the following fire zone centers:
engine compartment fire (fuel system) driver's compartment dashboard
fire (short circuit) passenger compartment fire (cigarette) box
compartment fire (heater)
In the past 30 years AUTÓKUT - even with international scale - became an outstanding bus expert in Hungary of developed bus construction technology and large-scale series production of buses. In spite of set-back of the patinated domestic bus manufacturers, according to international trends we performed and presently perform the following tests and researches in the past five years: lockability of passenger doors, fall-out protection; prevention of fall-out through windscreen and side window; fastening of passenger seats, installation with three-point belts thereof; development of bumpers; higher frame strength, application of stainless steel; detailed specification of roof strength requirements; development of passive safety procedures.
Since 1978 AUTÓKUT deals
with
development of the anti-jack-knifing equipment applicable for the
so-called articulated pusher buses. This equipment is to prevent the
undue jack-knifing of the vehicle in case of wheel slip. Several
solutions were born at functional diagram and design level, until we
developed the solution, that is a special detector sensing the steering
angular displacement and the articulation angle, as well as a digital
sensor/processor electronically evaluating the signals thereof. During
years several solutions, thus this latter too, obtained patent. A few
experimental equipment were installed into the Ikarus articulated
buses,
as well. On basis of the manufacturing, operation and maintenance
experiences obtained during the experiments, we started the development
of such an equipment, which was furnished with limited function
electronics - proved to cause the most problems earlier - and with
flexible "knowledge" (possibly) adaptive to the operation demands. The
test of the new dersign was implemented in an experimental
configuration, theoretically on working model and proved the
expectations. This experimental equipment served as base for producing
the first samples. The history of the equipment's becoming a product
really started with this.
The development was performed in
several steps. During this the below listed individual type versions
were developed.
Basically the development aimed
at
increasing the control's reliability, reducing the manufacturing costs,
optimizing the control electronics and reducing the service and
maintenance expenditure of time. During this we integrated the
initially
sectioned hydraulic control into one block. This, besides improving the
reliability, significantly reduced the manufacturing costs, as well. It
can be mentioned as innegligible advantage, that by this we could
reduce
the mass of the hydraulic control almost to the half of the initial
value. During development of the control electronics we succeeded in
realizing our aims. Thus an execution meeting the recent requirements
(compact, but small-size insulate metal case) was produced, indeed. The
equipment is undemanding in respect of service and maintenance, does
not
require developed service infrastructure. Its application features also
improved (programmable chip, comfort information functions). On basis
of the installation experiences we performed structural modification,
replacing the fixed cable of the approach detectors by plug-in one. By
this the sensor head "separated" from the cable, by which both the
service and the repair became significantly simpler.
With the increasing number of he
issued vehicles furnished with HB93
V3.0 type anti-jack-knifing equipment the number of the faulty or
negligent installations rapidly reduced. Among the units already
working in nearly 1000 buses, practically there was no malfunction due
to de- sign or manufacturing causes. The new concept basically is to
position each subassembly of the anti-jack-knifing equipment in the
articulation center. A direct outcome of the notion is to offer the
anti-jack-knifing equipment and the articulation center as integrate
mechanism. The main cause of this is the fact, that the currently used
configuration was developed for a special bus type and tailored to the
manufacturer's needs, i.e. the actuating hydraulic cylinders reach the
articulation center from the front part of the trailer. If an
autonomous
structural part - accommodating the anti-jack-knifing equipment, too -
can be installed to between the front and rear vehicle sections, the
equipment can be made independent of the vehicle.
Our present system my have serious odds on any market, namely the anti-jack-knifing equipment - owing to its simplicity, operational safety and relative low cost - is very competitive, even if selling together with the articulation mechanism.
The listed tests properly render
the
wideness and variegation of our field of activity.